There are many people in the Greater Toronto Area who have been given permission to posses or grow their own medical marijuana, but after the Conservative government changed the regulations to only allow for commercial growing of marijuana, several individual citizens filed a lawsuit. Fortunately, the federal courts have sided with the individuals, saying that anyone who already has a license to grow marijuana can continue to do so. This is important for anyone who is currently cultivating marijuana as medicine for themselves or others.
While Health Canada issued a warning that patients who grew their own marijuana would be reported to police if they did not destroy their plants, it is entirely possible that not everyone who has a license was aware of the change in regulations. This means that, had the injunction not come through, many people who thought they were complying with the Marijuana for Medical Purposes Regulations would actually have been at risk of criminal prosecution. It is unknown if anyone in Ontario was arrested and charged in the time between when the new regulations were enacted and when the injunction was handed down.
Regardless of how people feel about individuals growing their own medical marijuana, it is important that any rule or law changes are well publicized. If someone does not know that an action is illegal, it really isn't fair to prosecute them for it. Even though it isn't fair, there are many prosecutors who will still go ahead and charge someone with something they had no idea was illegal.
For anyone who has been criminally charged with marijuana cultivation, it would be wise to discuss one's legal options with a criminal defence lawyer. These charges are serious and can come with significant consequences.
Source: The Globe and Mail, "Federal Court grants injunction to allow patients to grow medical pot," James Keller, March 21, 2014